Monday, January 22, 2007

Starfruit tree

Starfruit tree

The starfruit tree (Averrhoa carambola) grows wild in Java and possibly in Borneo and the Philippines. However, there are people who believe that it originated from tropical America. Whatever its origin, the tree has been in cultivation for centuries and it has been grown in Singapore for a very long time.

This bushy, 15 metres tall tree is grown for its fruits that may be sweet or sour, depending on the cultivar (left). The tree flowers and fruits regularly throughout the year. The lilac flowers are small and borne in loose bunches (below). The fruit has five deep wings along its length and in cross-section appears star-shaped, thus the common name. It ripens golden yellow.

I have the tree growing in my garden for years now. The ripe fruits have always been attacked by fruit flies, falling on the ground to rot. It was some years ago that I noticed green, unripe fruits littering the ground below, always partley eaten. And then I noticed the visits of the noisy, white Tanimbar Corella (Cacatua goffini), an exotic species (below). These corella prefer the green, unripe fruits to the succulent ripe ones. They are wasteful eaters, pecking out pieces and leaving the many partly eaten fruits to rot below the tree. It would appear that this corella has exploited a food niche that other species of birds have been avoiding. It has similarly taking to eating the green pong pong fruits (Cerbera odollam) that no animals had previously been eating (see 1 and 2). The flowers of the starfruit tree attract ants, bees, moths and others (above), and these insects in turn attract birds. But I have so far failed to see many birds on this tree besides the corella. Except the smallish Common Tailorbird (Orthotomus sutorius) that regularly visits the tree, quietly gleaning for insects. The bird in the photo below is a male in breeding plumage, with long central tail feather and blackish sides to the neck. Now who says exotic plants do not attract wildlife?

If any birders have observed other birds visiting this tree, please leave your input here. Thanks.

2 Comments:

Richard Corlett of HKU has suggested that with the case of invasive birds, the animals tend to be not reliant on particular species of food plants but more on the fact that the new habitat offers a suitable 'structural' make-up (e.g., plenty/lack of undergrowth, good canopy cover, edge habitats), thus enabling the animals to establish themselves in a new locale (e.g. released babblers in Hong Kong, the laughing-thrushes in Kent Ridge Park). I would guess that in a mirrorred sort of way, introduced plants would quite easily fit the 'structural' needs of some of the local bird biota (e.g. sunbirds happily feed from Neotropical heliconias).

wow dun see that many birds around the starfruit tree at garden at the foot of blk s2 at NUS science near blk s1a. maybe i wasn't looking hard enough. there are bats and green necked pigeon and yellow crested cockatoo in the area but have not seen them nibble on the starfruit tree before. perhaps i wasn't alert enough